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T.P.D.M.V.2.4
(A1/92)
(i)
Where the combined, Heavy Goods Vehicle, Medium Goods
Vehicle, Bus and Coach traffic flow is predicted to
be less than 5$ of the design year AADT flow, subject
to paragraphs 4*6.7*8, 4.6.7.9 and 4.6.7.11* the
effective carriageway width may be reduced to 4.3m;
or
Cii) Where the combined, Heavy Goods Vehicle, Medium Goods
Vehicle, Bus and coach traffic flow is predicted to
be greater than 10J{ of the design year AADT flow,
subject to paragraph 4.6.7.11, the effective
carriageway width shall be increased to 6m, except
that where very high costs may arise, the standard
effective carriageway width of 5*2m may be provided.
However it will be necessary in this case to
substantiate the savings that would be obtained, and
provide details of the indications of adopting 5.2m
rather than 6m.
4.6*7.8 It should be noted that the 5.2m width will allow a goods
vehicle to pass a stationary car, but in the event of a goods
vehicle or bus breaking down it is unlikely that another goods
vehicle or bus would be able to pass the broken down vehicle.
Similarly, whilst the JJ.3m width will allow a car to pass
another stationary car, it is unlikely that a goods vehicle or
bus could pass the same stationary car. Therefore when
contemplating the use of an effective carriageway width less
than 6m, consideration should be given as to whether on the
particular single lane ramp or slip road there is for any reason
likely to be a higher breakdown incidence than normal, the
effects of which might be worsened if a too narrow width was
adopted. Consideration must also be given to the availability
of alternative routes which could be used to by-pass the
obstruction. The Public Transport Planning Division of the
Transport Department should be consulted to ascertain whether
there is any likelihood of a bus route being required at any
time in the future, which might be prejudiced if an inadequate
operational width was provided.
4.6.7.9 Where single lane ramps or slip roads are greater than 50m in
length the effective carriageway width should not normally be
less than 5»2m»
4.6.7.10 Where single lane ramps or slip roads are greater than 100m in
length the Traffic Control and Surveillance Division of the
Transport Department should be consulted to ascertain whether
surveillance measures need to be included in the scheme.
4.6.7*11 To ensure adequate clearance between any vehicle and the
parapets, and to maintain the passing requirements mentioned in
paragraph 4.6.7.8 the effective carriageway widths should be
widened on curves in accordance with Table 4.6*7.2.